A fusing apparatus for an image forming apparatus includes a fusing belt which rotates, a bushing guiding the fusing belt, a ring member rotatably coupled to the bushing and in contact with the fusing belt so as to rotate together with the fusing belt, and a sliding guide member, provided between the ring member and the sidewall of the bushing and at least partially disposed above a central axis of the fusing belt. The sliding guide member slidably supports the ring member and protrudes from the sidewall of the bushing such that a continuous gap is provided from a bottom of the sliding guide member to a bottom of the sidewall of the bushing.